"We have done lectures at colleges and they'll play that song and we're like, 'Can you just turn that off' — drives us crazy — because we're so not that," Wilson said.

Hawes and Wilson have captured images of ghostly shadows in New England lighthouses and glimpses of eerie apparitions in Michigan cellars. They have also caught their share of flak from skeptics.

"I don't care at all what the skeptics think of what we're doing because they don't need help," Wilson said. "There are people who need help in their homes. Who's helping them? Are the skeptics going to help them? No!"

Hawes also sees their work as a community service.

"Whether they're rich, whether they're poor, all the people out there who believe that they have paranormal issues need help," he said.

Hawes and Wilson have been hunting ghosts on their own for nearly two decades. It all began after they encountered a few paranormal experiences of their own, experiences they didn't want to talk about. The phenomena inspired them to found TAPS: The Atlantic Paranormal Society, a group that tries to help people who think their house, farm, garage or anything might be haunted.

"We are not looking for ghosts," Wilson said. "We're looking to disprove them."

"We're looking for explanations," said Hawes.

'Plumbing Does Come in Handy'

Their day job doesn't have anything to do with ghosts. Wilson and Hawes are plumbers—who happen to be interested in flushing out the paranormal.

"This is a hobby that we do," Wilson said. "The plumbing does come in handy because people say their dead Uncle Fred is flushing the toilet at night. We go in there and tell them they've just got a bad flapper valve, fix it, and magically the ghost disappears."

Ghost hunting, at a certain level, is one big audiovisual project -- seeing and hearing is believing. Hawes and Wilson bring a ton of recording equipment on their calls, including thermal cameras that are thought to catch signs of paranormal activity not visible to the naked eye.

"When we can't explain it away…then we've got some evidence that we can really bring to the public and say, 'What do you think this is?'" Wilson said.

The Scariest Hotel in the U.S.

The Ghost Hunters had some of their most memorable experiences while staying at what is thought to be one of the most haunted buildings in America, the Stanley Hotel in Colorado, built in 1906.

For generations guests have told tales of voices, shadows and books flying off the shelves. It is filled with so much ghostly speculation that horror master Stephen King wrote "The Shining" after spending a night there.

It was during a taping of "Ghost Hunters" at the Stanley when a closet door opened on its own and a glass shattered while Hawes was sleeping.

"Now you got to remember just because a door opens and closes on its own and a glass shatters doesn't mean that there was a ghost, we didn't catch a ghost, we caught those things happening," Wilson explained. "We can't explain why they happened and that's why its unknown, so we'll leave it at that. If someone can tell us why that happened then great we have more information for the next case."

Wilson said he believed in spirits and ghosts, but he doesn't believe every story brought his way.

"It always blows my mind how people hear a bump in the night… and instead of just going, man, maybe that's plumbing, they jump way high and say it's a ghost," he said.

Hawes also believes in ghosts -- and hauntings.

"We've got every religion, every nationality pretty much out there that has talked about this for the longest time. There's got to be some truth behind that," he said.

Journey Into the Unknown

Wilson and Hawes recently traveled back to the Stanley Hotel and gave "Nightline" the grand tour. The first stop? A creepy basement.

The Ghost Hunters navigated deftly past various plumbing mechanisms, making their way into the bowels of the building. Grant hoped to reconnect with a little girl rumored to haunt the Stanley basement by speaking in a kind, caring language she could identify with. The girl died in the 1920s.

Last time Wilson and Hawes visited the basement they allegedly caught her voice on a tape recorder, but this time they didn't hear anything while in the basement. It's enough to make the average person a little scared, but not the Ghost Hunters.

"Just like in plumbing, you never know what you're about to walk into. Every case is a challenge," Hawes said.

Wilson admitted it's not all just in a day's work.

"When you are investigating, you don't get scared, but you do get surprised sometimes, you do get shocked," he said. "Something pops out in front of you or something moves suddenly. Hey, you're not expecting it, but it doesn't mean you're scared," he said.

The Ghost Hunters have seen a lot that cannot be explained during their inspections. On their last visit to the Stanley, a table seemed to jump out from underneath Wilson.

"No matter what we ever catch, will it be enough to prove to the skeptic, the skeptical world that there's ghosts?" Hawes asked. "No, because anybody can shoot down anything they want. They can try to recreate anything they want. But, you know what, it's enough for me to believe, it's enough for him…the other people involved within the society. And it's enough for the people who called us in to help them."

"I don't care at all what the skeptics think of what we're doing," said Wilson.

Both men said they're in it for the long haul. Wilson plans to keep ghost hunting for as long as he remains healthy. And as for Hawes?

"I'll ghost hunt until the wife and my kids tell me it's time to stop," he said.